This PR was squashed before being merged into the 4.x branch.
Discussion
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[Twig 4] Add PHPUnit as dev dependency
This makes it easier to run the tests locally.
I understand we didn't do this previously (Twig 3) because of `symfony/simple-phpunit`. But that is now removed in Twig 4, so maybe we can do this as well?
Commits
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c352a8d283 [Twig 4] Add PHPUnit as dev dependency